The greatly increased variance, but only somewhat increased mean, is consistent with nicotine operating on me with an inverted U-curve for dosage/performance (or the Yerkes-Dodson law): on good days, 1mg nicotine is too much and degrades performance (perhaps I am overstimulated and find it hard to focus on something as boring as n-back) while on bad days, nicotine is just right and improves n-back performance.
Since Racetams result in increased uptake and demand for acetylcholine, stacking choline with this nootropic will further enhance your results. Studies have shown that choline supplementation can improve performance on memory tests as well as social behavior. Choline also plays a key role in the production of phospholipids that are incorporated into brain cell membranes.
The low-carb & high-fat diet (includes keto-diet) are not good for you because the brain needs glucose for fuel. It can burn fat. But, the brain’s preferred energy source is glucose. The key is to provide the brain with glucose without raising glucose/serum blood level. You do that by avoiding sugar and eating complex carbohydrates (fresh produce) that convert into glucose.

The soft gels are very small; one needs to be a bit careful - Vitamin D is fat-soluble and overdose starts in the range of 70,000 IU36, so it would take at least 14 pills, and it’s unclear where problems start with chronic use. Vitamin D, like many supplements, follows a U-shaped response curve (see also Melamed et al 2008 and Durup et al 2012) - too much can be quite as bad as too little. Too little, though, is likely very bad. The previously cited studies with high acute doses worked out to <1,000 IU a day, so they may reassure us about the risks of a large acute dose but not tell us much about smaller chronic doses; the mortality increases due to too-high blood levels begin at ~140nmol/l and reading anecdotes online suggest that 5k IU daily doses tend to put people well below that (around 70-100nmol/l). I probably should get a blood test to be sure, but I have something of a needle phobia.

2ml is supposed to translate to 24mg, which is a big dose. I do not believe any of the commercial patches go much past that. I asked Wedrifid, whose notes inspired my initial interest, and he was taking perhaps 2-4mg, and expressed astonishment that I might be taking 24mg. (2mg is in line with what I am told by another person - that 2mg was so much that they actually felt a little sick. On the other hand, in one study, the subjects could not reliably distinguish between 1mg and placebo25.) 24mg is particularly troubling in that I weigh ~68kg, and nicotine poisoning and the nicotine LD50 start, for me, at around 68mg of nicotine. (I reflected that the entire jar could be a useful murder weapon, although nicotine presumably would be caught in an autopsy’s toxicology screen; I later learned nicotine was an infamous weapon in the 1800s before any test was developed. It doesn’t seem used anymore, but there are still fatal accidents due to dissolved nicotine.) The upper end of the range, 10mg/kg or 680mg for me, is calculated based on experienced smokers. Something is wrong here - I can’t see why I would have nicotine tolerance comparable to a hardened smoker, inasmuch as my maximum prior exposure was second-hand smoke once in a blue moon. More likely is that either the syringe is misleading me or the seller NicVape sold me something more dilute than 12mg/ml. (I am sure that it’s not simply plain water; when I mix the drops with regular water, I can feel the propylene glycol burning as it goes down.) I would rather not accuse an established and apparently well-liked supplier of fraud, nor would I like to simply shrug and say I have a mysterious tolerance and must experiment with doses closer to the LD50, so the most likely problem is a problem with the syringe. The next day I altered the procedure to sucking up 8ml, squirting out enough fluid to move the meniscus down to 7ml, and then ejecting the rest back into the container. The result was another mild clean stimulation comparable to the previous 1ml days. The next step is to try a completely different measuring device, which doesn’t change either.

The blood half-life is 12-36 hours; hence two or three days ought to be enough to build up and wash out. A week-long block is reasonable since that gives 5 days for effects to manifest, although month-long blocks would not be a bad choice either. (I prefer blocks which fit in round periods because it makes self-experiments easier to run if the blocks fit in normal time-cycles like day/week/month. The most useless self-experiment is the one abandoned halfway.)
The basic idea is to remedy a deficiency (not look for acute stimulant effects) and magnesium has a slow excretion rate18, so week-long blocks seem appropriate. I can reuse the same methodology as the lithium self-experiment. The response variables will be the usual mood/productivity self-rating and, since I was originally interested in magnesium for possible sleep quality improvements, a standardized score of sleep latency + # of awakenings + time spent awake (the same variable as my potassium sleep experiment).
In general, I feel a little bit less alert, but still close to normal. By 6PM, I have a mild headache, but I try out 30 rounds of gbrainy (haven’t played it in months) and am surprised to find that I reach an all-time high; no idea whether this is due to DNB or not, since Gbrainy is very heavily crystallized (half the challenge disappears as you learn how the problems work), but it does indicate I’m not deluding myself about mental ability. (To give a figure: my last score well before I did any DNB was 64, and I was doing well that day; on modafinil, I had a 77.) I figure the headache might be food related, eat, and by 7:30 the headache is pretty much gone and I’m fine up to midnight.
The evidence? Found helpful in reducing bodily twitching in myoclonus epilepsy, a rare disorder, but otherwise little studied. Mixed evidence from a study published in 1991 suggests it may improve memory in subjects with cognitive impairment. A meta-analysis published in 2010 that reviewed studies of piracetam and other racetam drugs found that piracetam was somewhat helpful in improving cognition in people who had suffered a stroke or brain injury; the drugs’ effectiveness in treating depression and reducing anxiety was more significant.
Dark chocolate. Let's end with the good stuff. Dark chocolate has powerful antioxidant properties, contains several natural stimulants, including caffeine, which enhance focus and concentration, and stimulates the production of endorphins, which helps improve mood. One-half ounce to 1 ounce a day will provide all the benefits you need, says Kulze. This is one "superfood" where more is not better. "You have to do this one in moderation," says Kulze.
l-Theanine – A 2014 systematic review and meta-analysis found that concurrent caffeine and l-theanine use had synergistic psychoactive effects that promoted alertness, attention, and task switching;[29] these effects were most pronounced during the first hour post-dose.[29] However, the European Food Safety Authority reported that, when L-theanine is used by itself (i.e. without caffeine), there is insufficient information to determine if these effects exist.[34]